The invention relates to a braking retardation apparatus for doors, windows or the like comprising a piston pressable into a cylinder against the force of an expelling spring, with the element to be braked acting on the piston rod of said piston.
Braking retardation apparatuses or damping apparatuses of this kind are used, for example, to brake doors and in particular doors of pieces of furniture just before their closing position in order to moderate the impact effect and to ensure the gentlest possible closing. Braking retardation apparatuses are used in particular when the doors and doors of pieces of furniture are provided with closing apparatuses which press said doors into their closing position and hold them in it. Braking retardation apparatuses of the kind first given can, however, also be used for other parts, in particular parts of pieces of furniture, for example for drawers or flaps to prevent these from reaching or hitting their end positions with force and irritating noise. From DE 197 17 937 A, a braking and damping element for moving parts of pieces of furniture of the kind first given is known which comprises a piston movable and spreadable in a radial direction in a cylinder, which piston is designed in such a way that compression of the air performed by the pushing in of the piston effects a radial extension or spreading of the piston, by means of which, in addition to the damping effect due to the compressed air, a braking effect is also caused by friction of the piston on the inside wall of the cylinder.
From DE 37 29 597 A1, a door-closing damper of the kind first given is known which comprises a brake cylinder fixed in the doorframe and a piston having an integrally formed ram which first compresses the air in front of the piston when the door is closed, the air being decompressed after a partial distance by means of a journal sliding through the piston and having a different diameter.
The known braking retardation apparatuses do not only have a complex design, they also require the manufacture of their individual parts with high dimensional accuracy in order to ensure their function. The manufacture of the known braking retardation apparatuses is therefore comparatively expensive.
It is therefore the object of the invention to provide a braking retardation apparatus of the kind first given which can be manufactured at a favourable price with reduced effort.
This object is solved in accordance with the invention by a grease having a high viscosity being applied to the wall of the cylinder.
The grease of high viscosity generating the braking or damping effect and applied to the wall of the cylinder belongs to the so-called damping greases. It is applied to the inside wall of the cylinder so that it effects the damping or retarding in the interior space between the wall and the piston. The grease of high viscosity used in accordance with the invention can comprise a base oil of high viscosity, an adhesive polymer and synthetic hydrocarbons with high viscosity so that it generates the desired frictional force between the piston and the cylinder when movement occurs.
As the grease of high viscosity used in accordance with the invention also contains an adhesive polymer as a component, it adheres well to the wall of the cylinder without being displaced in a manner such that it could no longer generate its braking effect. In addition, there is so much play between the wall of the cylinder and the piston that the grease develops the effect of a sliding guide without being displaced to any real extent.
The grease of high viscosity used in accordance with the invention provides not only dust protection, but also an effective seal so that the use of additional sealing agents or sealing equipment can be dispensed with.
Appropriately, the wall of the cylinder is provided with annular or spiral channels or grooves which prevent any unwanted transposition of the grease. The wall of the cylinder can also consist of an uneven surface which has, for example, recesses in a given pattern and which also prevents any unwanted transposition of the grease.
Instead of the wall of the cylinder or in addition to the wall of the cylinder, the circumferential surface of the piston can also be provided with annular or spiral channels or grooves or have irregularities.
The cylinder can be closed by a cover, e.g. by a screw plug. This screw plug forms the bottom of the cylinder, between which and the piston the expelling spring is clamped. The expelling spring formed by a compression spring can be designed to be very weak and the force of this spring is overcome in the closed state, for example of a door, by its closing mechanism. In accordance with the only weak design of the expelling spring, the expelling movement of the piston takes place accordingly slowly.
The cover closing the cylinder can be provided with a venting borehole which allows a more gentle movement of the piston.
The piston rod appropriately penetrates a borehole of the front wall of the cylinder, with the ring step between the borehole edge and the cylinder wall forming a stop for the piston.